Sayyiduna Jabir said: The Prophet (peace and blessings be upon him) used to say the takbir every time he bent down and every time he rose.
Imam al-Bazzar recorded it; its narrators are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2793